Quality: Silver Tier.
🐙 userver provides access to Apache Kafka Brokers via two independent interfaces: kafka::ProducerComponent and kafka::ConsumerComponent.
They expose APIs for sending messages to Kafka topics, suspending coroutine until message delivery succeeded or failed, and for process message batches from the subscribed set of topics, asynchronously polling messages in separate task processor.
Common Features
- Easy to configure (compared with raw Kafka clients with dozens of options);
- No message payload copying;
- Support of SASL SCRAM-SHA-512 authentication and SSL transport for Broker communication;
- Comprehensive logs of all events and errors;
- Metrics;
Producer Features
- 🚀 Parallel cooperative messages delivery reports processing (in comparison with all librdkafka-based Kafka clients, the performance of which rests on a single thread);
- 🚀 No blocking waits in implementation (message senders suspend their coroutines execution until delivery reports occurred);
- Synchronous and asynchronous non-blocking interfaces for producing messages;
- Automatic retries of transient errors;
- Support of idempotent producer (exactly-once semantics);
- Sending message to concrete topic's partition;
Consumer Features
- 🚀 No blocking waits in implementation (message poller suspends the coroutine until new events occurred);
- Callback interface for handling message batches polled from subscribed topics;
- Balanced consumer groups support;
- Automatic rollback to last committed message when batch processing failed;
- Partition offsets asynchronous commit;
Planned Enhancements
- ✅ Transfer from raw polling with timeouts to events processing, making the message polling non-blocking and leading to better library scalability;
- ✅ testsuite Kafka support in OSS;
- Support of different compression codecs (GZIP, LZ4, ZSTD, etc..);
- Support more SASL authentication mechanisms (GSSAPI, OAUTHBEARER);
Unit and functional testing
- Kafka service shows how to test userver services with Kafka consumers and producers;
- kafka::utest::KafkaCluster may be used for convenient unit testing with local consumers and producers instances;
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